So, I have a 97 maxima with the electronic climate control and 145K miles. When I got the car, it was stuck blowing out of the defrost vents at full heat. I have been digging around and found that someone had disconnected the blend door for directing air to the floor. I found the heater blend door and disconnected the lever so I could move it manually. Still blowing out of the defroster vents though and it doesn't respond to any of the controls.

I find it difficult to believe that every single blend door went out at the same time. Any ideas on what could be causing this?

 

Ok, I did a search and found the diagnostic stuff. I have code 25 and 26, then code 31-32-33-34.

 

your terminology makes diagnosing this a bit weird, but it sounds likely that it is your mode motor, which is what switches the doors open and closed.

 

Sorry, I am more used to fords terminology in the HVAC system. I checked the terminology here and have it figured out. Someone disconnected the mode motor, but the shaft doesn't turn when commanded by the climate control module. In addition to that, the heat/cold blend door motor isn't functioning when commanded. Lastly the sun load sensor isn't functioning and something about the PBR isn't functioning either.

I checked all of my fuses and they are all fine. So I am guessing that it's either the climate control module has gone bad. Or both the mode motor and the blend door motor have gone out. Is there any way of testing the climate control module?

 

i would start with going to the JY and grab 2 mode motors and swap yours and see how that does her.

 

Took the mode door motor out and apart. Applied direct power to the motor and it spins fine. Guessing my control module **** the bed.

 

The PBR is inside the motor that moves what you are calling the heat/cold blend door. Nissan has decided to call that the air mix door, in case you were curious.

The only way I know how to test the control panel is to swap it with another one.

I would get another control panel before buying any motors.

 

Bought one off from ebay. This past week I have done a heater core/blend door in an 00 F150, a blend door motor in a 97 ford explorer, A/C compressor on a 95 Geo Prizm, now the maxima, and the a/c just went out in my 97 mustang cobra. HVAC has been giving me fits recently lol. Oh and I forgot that I just put a transmission in this maxima.

 

Well, I plugged in the new climate control module, keyed on and the mode door motor moved. Put the mode door motor back on, keyed on and it was blowing out of the vents. Thought it was fixed, but I was wrong. Now it only blows out of the vents and the aix mix door is still non functional. Ran the diagnostic again and this time I have code 31-32-33-34-35.

 

Starting to think the BCM is bad. I know for a fact that my mode door motor works, I am assuming that the push button unit works, that leaves the BCM. It would make sense too because the other day, the doors just randomly locked on me, had to break into my own car. I don't have a remote, so it couldn't be that.

 

Just for clarification, does your fan speed change now, or was it ever stuck at full blast? Blower resistors will correct that issue, but yours sounds deeper.

 

I don't think the ACC module has any blower resistors.

OP: You're using the self-diagnostic that is done with the ACC unit itself?

 

The blower has always worked fine. It's the air mix and the and the mode door motor's that aren't working. With the original push button unit, I was stuck on defrost mode, when I put the new unit in, it automatically went to the vents, but won't change.

Yes, I am doing the self diagnostic with the ACC module. The ACC communicates with the AC Auto Amp, which is what controls basically all of the climate control functions and the AC Auto Amp is part of the BCM.

 

If the wire harness for the mode door motor is disconnected, you will get the 31, 32, 33, 34, 35 errors, so double check the connections. However, after you replaced the control panel in the dash and got different error codes with the self diagnostic, it makes me question that replacement control panel.

You are correct when you say the auto amp is part of the BCM. If you are going to get another BCM, make sure that it is for the auto climate control as the BCM for the manual controls will not have the auto amp portion.

If you want to get used parts, there is an org member, Maxima Joe, who sells them. Send him a PM.

 

I double checked all of the connections and they are fine. The previous error codes were only missing 35, which is defrost, which is where it was stuck. I am thinking since it moved, that is why code 35 is new. Everything else is the exact same code wise. I am thinking about hitting my local pick N pulls, see if I can find a BCM, if not, I will PM him.

 

Well, I went to the pick N pull and got two BCM's to test with. No change with either one, I used both my original head unit and the replacement on. I am REALLY getting pissed off here, I have dealt with some ****ty HVAC before, but this one has to take the cake.

 

Have you tried KNOWN WORKING acc unit?
Where'd you get the one you have now, just ebay, no idea of it's history?

Also when "checking the harnesses", what does that mean to you? Are you just making sure they're connected, etc? Or are you doing the tests listed in the FSM? Actually checking resistance, etc.

 

Also, this seems silly to ask given you have the codes, etc in front of you, but you ARE using THIS, right?

http://www.nicoclub.com/FSM/Maxima/1997/HA.pdf

Have you forced the codes 40,41,42, etc? these force an output to the actuators for the motor. Any time you get a 31,32, etc code the unit shuts down motor operation until it's repaired.
Doing the 40,41 test bypasses that shut down and operates them anyways so you can diagnose it more.

 

 

No, I don't have a known working ACC unit. Yeah, I just ebayed the ACC unit and he claimed that it was working, but you never know. I intend on taking those BCM's back to the JY and getting another ACC unit as well as a new mode door motor and air mix motor. Should be fun getting those out.

I have tested for a ground, which I have and when power is applied direct, the mode door motor moves, which is why I thought ACC or BCM.

Yes, I used the self diagnostic as described at the nico link and yes I tried to command them directly with the 40 codes and they still didn't work.

 

Did you do Diagnostic procedure 4 and 5 as illustrated in my last post?
That's checking for more than just ground and bypassing power.

There's a few components at work here, you seem like a smart cat, and might be caught in the trap we all get caught in when working on something like this. You're assuming stuff, and throwing parts at it.
That's not an insult, at all. I do it, even though I know better. AND most times you can get away with it if your guess at the part is educated.

HOWEVER, this clearly hasn't been working for you so far, so you need to step back and re-engage EXACTLY as the FSM states you should, follow it precisely, and do it twice just to make sure you did it right.

The FSM procedure will directly lead you to the component at fault, at that point, you can replace it.

I'm not saying it is/isn't the ACC unit, or anything like that. BUT if you are skipping vital steps in diagnostics then you are only screwing yourself over. I've learnt that the hard way a few times
I still do it once in a while because following all the precise checks they want can be a PITA. But it does work.

 

THIS.

I do electronics troubleshooting and repair for a living and Tuner is spot on...sometimes I've made assumptions that turn out to be wrong when I go back after hours of troubleshooting with an open mind and calm demeanor and a fresh set of eyes find the problem right quick

 

I admit that I do have a tendency to throw parts at something. Will go back to basics, do the FSM tests and report back with the results.

 

Good luck dude, report back! And take deep breaths

 

Sorry for not getting back sooner, had a cold. Did the tests. No 5V on pin 3 of the air mix door, continuity exists between pin3 on the air mix and pin 7 on the BCM. Solution, replace BCM. I guess my instincts were right, but my luck is rotten, getting two bad BCM's from the junkyard.

 

4th gen is known for BCMs. And they're different year to year IIRC, but don't cite me on that, my 4th gen knowledge is old and crusty.

 

97-99 are the same. Going back to the JY and see if I can't find a decent one.

 

Well, I reached a happy medium. Got another BCM, which didn't work, so I decided to just wire in a momentary toggle switch to control the air mix door. Once I got it wired in, the motor still wouldn't move, so in a fit of rage, I held the switch down and bashed the motor with a screwdriver until it started moving. After that, the stock system will control the temperature. I can live without defrost or floor controls.

 

The more I think about this, the more I wonder about that motor.